Circuit breaker



June 28, 1955 j w, WELSH 2,712,044

CIRCUIT BREAKER Filed Aug. 18, 1953 the vane except at its attachmentpoints thereto.

United States Patent 0 CIRCUIT BREAKER James W. Welsh, Summit, N. L,assiguor t0 Signal-Stat Corporation, Brooklyn, N. Y., a corporation ofNew York Application August 18, 1953, Serial No. 374,920

13 Claims. (Cl. 200-122) filed August 18, 1953, for Snap Action Device,I have shown and described a novel conductive metal snap action vanewhich may be incorporated in a snap action switch. This vane is providedwith an initial bend about a right line extending across the vane bythinning or deforming the vane along this line in two or more spacedsections of the line, these sections being spaced at their inner endsfrom the center of the vane and also preferably spaced from the outerends of the bent line. When such a vane is to be utilized in a snapaction switch, such as a flasher, the vane is forcibly bent aboutanother line, at an angle to the line of initial bending by applyingforce to the ends of such lines of initial bending. When such force isreleased, the vane snaps back to its initial bent position, the actionclosely resembling that of a toggle.

With a vane initially deformed in such a manner, the locked up stressesor forces having locii on elliptical lines or zones having radiicentered on the center or midpoint of the vane located on the line ofinitial deformation midway between the inner ends of the spaced ofdiscontinuous deformation. If the vane is held or fixed at a point onone of these locii, the remainder of the vane, during snapping thereof,pivots about such mounting point. The greatest effective forceis-exerted at the center of the locii, but very substantial force isalso exerted by portions of the vane located on the 'locii at theopposite side of the deformation line from the fixed mounting point.

Such a vane may be effectively used in a thermostatic snap action switchby restraining the vane in the stressdeformed position by attaching ahigh resistance wire or strip at each of its ends to the vane at theends of the line of initial bending. This high resistance wire or stripthus forcibly holds the vane in a distorted position bent about a lineangularly related to the line of initial bending. When the highresistance wire has electric current passing therethrough, it heats andexpands. During the expansion of the wire, a point is reached at whichthe tension exerted by the wire is overbalanced by the kinetic energy ofthe vane stored therein by bending the latter from its initial bentcondition. At this point, the vane snaps back to its initially bentcondition.

When the wire is holding the vane in the stress-deformed position withthe vane bent on a line at an angle to the line of initial bending, thewire is spaced from As the wire expands to the point where the vanesnaps back to its original pre-set or restored position, the wire snapsinto linear contact with the vane. The wire, intermediate its end orvane attachment points, thus moves inward and outward r the snappingaction of the la tive to the mounting or pivoting point of the vane.Thereby, a make and break switch action can be prov1dcd by mounting onecontact of the switch on the wire intermediate its ends, and mountingthe cooperatrve contact in fixed relation to the vane mou pivot point,as by mounting tively rigid bracket or mounting member secured to thevane at a point laterally of the deformation line or on one of thestress contraction locii.

My co-pending application Seriai No. 374,918, filed August 18, 1953,illustrates such a snap action switch or flasher having parameters sothat the two contacts are held in full pressure engagement, or evenunder increasmg pressure, during the time resistance wire is heating andexpanding and right up to the instant that the vane shapes back to itspreset condition. Thus there 18 no diminution or reduction of contactpressure during the 1nitial part of the switch opening movement orcycle, and full pressure is maintained between the contacts until theyare snapped apart by the snap action of the vane in restoring itself toits preset deformation.

More specifically, the switch parameters are so selected that, when thecontacts are engaged, and up to the time that the snap action takesplace, the resistance element 18 depressed at its center toward thevane, so that the center of the element exerts a force component in thedirection of the contact carried by the vane mounting means. By properselection of the switch parameters, this contact pressure effectingforce may be made to increase during the expansion of the resistancewire so that at least full contact pressure is maintained up to theinstant the snap action of the vane occurs.

At such instant, the contacts are snapped apart, thus instantaneouslymoving the contacts from the full pressure engaged position to a widelyseparated circuit breaking position. Thereby, with such arrangement, aplot of the current flowing across the contacts versus time willessentially resemble a square wave portion of the curve to the currentportion of the curve.

The switch shown and described in said application Ser. No. 374,918, isparticularly designed as an on-off flasher for lamp circuits, such asthe signal lamp circuits of automotive vehicles. Actually, however, suchswitch is also a very good circuit breaker under complete short circuitconditions, due to its excellent contact-pressuremaintaining, and snapaction contact opening and closing characteristics. Thesecharacteristics allow the switch to operate satisfactorily even undersever short circuit or overload conditions. However, it has thedisadvantage that, when used as a circuit breaker, it will ultimatelyfail due to burning through of its contacts as the result of itsalternating on-ofl' action. While this is not serious from a safetystandpoint, as the switch will fail safe in the open contact position,it is desirable, in a circuit breaker, that the contacts, when opened onoverload or short circuit, remain open until the condition causing theoverload or short circuit is removed.

In accordance with the present invention, a novel modification of thethermostatic switch of said application Ser. No. 374,918 is provided,whereby the latter forms an eflicient circuit breaker which does notrequire manual re-setting or replacement after a short circuit conditionhas been cleared. More particularly, the switch actuat ing elementcomprises a normally contracted, heat expansible element or strip whichis indirectly heated by a high resistance wire connected in shunt withthe switch contacts. The indirectly heated operating element normally isin a contracted condition constraining the snap action vane to thestress-deformed condition in which a contact mounted on the element isheld under high preselative to the vane during tter, and particularlyrelanting or the vane contact on a relasure engagement with a contactfixed relative to the vane mounting point. Under normal load conditions,the current fiow drawn through the relatively low resistance operatingelement is insufiicient to heat and expand the same sufiiciently topermit the vane to snap to its pre-set or restored conditions.

However, under short circuit or heavy overload conditions, thesubstantially increased current flow through the operating element, orpull ribbon, will heat and expand the same to an extent suificient toallow the vane to snap to its restored condition, snapping open thecontacts. The current then flows through the high resistance wire and,being relatively high in value, provides sufficient heat to the pullribbon to maintain the same ex panded. When the short circuit or heavyoverload condition is cleared, the reduced or interrupted current flowthrough the heating wire reduces the heating of the pull ribbonsufliciently to allow the latter to contract to an extent where it snapsthe vane back to the stress-deformed condition to re-close the circuitbreaker. Thus, no manual re-setting is required.

For an understanding of the invention principles, reference is made tothe following descriptions of typical embodiments thereof as illustratedin the accompanying drawings.

In the drawings:

Fig. 1 is a perspective view of a snap action vane and its mountingmember as used in the invention switch arrangement;

Fig. 2 is a transverse sectional view of the vane of Fig.

1 with the invention operator and its heating means secured thereto;

Fig. 3 is an elevation view of one form of indirectly heated vaneoperator embodying the invention view corresponding to Fig. 2;

Fig. 4 is a transverse sectional view on the line 4--4 of Fig. 3;

Fig. 5 is a longitudinal sectional view of another form of indirectlyheated vane operator;

Fig. 6 is a transverse sectional view on the line 66 of Fig. 5;

Fig. 7 is an elevation view of still another form of operator embodyingthe invention;

Fig. 8 is a perspective view of a snap action circuit breaker embodyingthe invention; and

Fig. 9 is a sectional view on the line 99 of Fig. 8.

Referring to Fig. 1, which is substantially identical with Fig. 10 of myco-pending application Ser. No. 374,976, a snap action vane 10 isillustrated which is identical with that shown and described therein.Vane if; is preferably of relatively thin electrically conductive springmetal, with consideration being given to its spring factor, stillness,temperature coefiicient, and the like, in accordance with the desiredrate of operation of the snap action.

To provide an initial set to vane 10 and to give the same some depth sothat it will resemble a beam in its action, the vane ltl, which is shownas a substantially rectangular vane, is deformed or thinned alongdiagonal interconnecting corners 11 and 12. This vane deformation ispreferably effected by linearly embossing the vane along the line 11--12in two elongated spaced portions or bosses 15. It will be noted that thebosses 1.5 have their inner ends disposed substantially equal distancesfrom the center of vane 14) so that the center area of the vane is leftunmarred. This greatly prolongs the life of vane 16 by removing thestress concentration from the center to a pair of points on bosses 15.If the deformation line 1112 were continuous through the vane centerarea, the flattening of the vane at the center during repeated cycleswould eventually cause fatigue of the vane at the center and reduce theamount of force required to snap the vane between the illustratedposition and another deformed position.

Due to the bosses, 15, 15, the sections 13 and 14 of the cuit for thevane operator.

vane on either side of line 1112 bend upwardly so that the vane assumesthe form of a shallow V having its apex on line 1112. When vane bendingforces are applied to the end of line 1112, and the value of theseforces equals or over-balances the inherent tendency of the vane to stayin its present condition, the vane snaps into a new bent or deformedposition, forming another shallow V along the other diagonal 16-17. Whenthe forces at points 11 and 12 are decreased to a point where they areoverbalanced by the kinetic energy stored in vane'ltl due to suchdistorting force, the vane snaps back to a position bent along the line1112.

Photographs, taken with polarized light, of a transparent vane formed inthis manner show lines of force in the unmarred center area of the vanewhich comprise elliptieal bands having radii centered on the vanecenter, if the vane is secured or supported at a point on one of theseelliptical stress locii, the stress points on the vane duringapplication of bending force at corners 11 and 12 occur within thelength of bosses 15. Thus the stresses are removed from the center areaand distributed between two points spaced from the center. This greatlyprolongs the period before fatigue takes place in the stressed sectionof the vane.

Advantage is taken of this fact by supporting the vane by electricallyand mechanically securing the latter at a point on one of suchelliptical lines of force, to a relatively rigid electrically conductivemounting, member or bracket 21?, the point of attachment of the mountingmember to the vane acts as a pivot point for the vane during its snapaction and is preferably spaced laterally of the initial bend line11-12.

When the vane is used to form a snap action switch, the bending stressesmay be conveniently applied to points 11 and 12 by means of a heatexpansible element 40 secured to these corners of the vane. For thispurpose, the points 11 and 12 are bent downwardly as illustrated in Fig.1 and the ends of the element are secured thereto at 31 and 32, whilethe vane is bent along the line 16-17, so that the element in its coldor contracted position, holds the vane deformed into a V having its apexalong lines 16 and 17. If the element is heated, it expands and, as thewire force is overbalanced by the restoring kinetic energy built up invane 18, the vane snaps back to its initially bent condition along theline 11-12.

in accordance with the invention, an indirectly heated. heat expansibleelement 40 preferably of conductive metal, is secured, in contractedrelation, to the corners 11 and 12 of vane 10, as at the points 31, 32.Such arrangement may be, for example, by soldering or spot welding theends of element 40 to vane 10 at points 31, 32 and is effected while thevane is stress-deformed about the diagonal 1617. Thereby, when element40 is heated and expanded a predetermined amount, the

kinetic energy in vane 10 will overbalance the tension of element 40 andsnaps the vane to its restored position in which it is bent about thediagonal 11-12. I

The indirect heating is effected by operatively asscciating an insulatedhigh resistance wire 3% with element 40. The length of the wire isindependent of the length of element and the parameters of vane 10, andis conditioned solely by the amount of resistance it is necessary ordesirable to include in the heating cir- In the embodiment of Figs. 2,3, and 4, element 40 is a channel shaped strip having resistance wire 30extending therethrough and with its end brought out of the channel atselected points in accordance with the desired switch contact andcircuit arrangements.

Figs. 5 and 6 show an alternative arrangement in which the pull stripsecured to vane corners 1 1 and 12 comprises a pair of mating strips orribbons a, 4515 each having a central groove 46 therealong. An insulatedhigh resistance wire 30 is enclosed'in grooves 1:; 46 and strips 45a,4511 are then welded together to form a composite pull ribbon 45.

A third embodiment of the indirectly heated pull strip arrangement isshown in Fig. 7. In this instance, the pull strip is an expansible Wire50 having a dielectric sleeve 51 thereon. High resistance wire 30 which,in this instance, may be bare, is wound helically on sleeve 51.

Figs. 8 and 9 show a snap action circuit breaker embodying theindirectly heated pull strip or ribbon 40 of Figs. 2, 3 and 4, althoughthe pull strips 45 or 50 could equally well be used therein. Bracket 29has one end secured to the surface of vane 10 having pull strip 40extending thereover, and at a point laterally of diagonal 11-12 andpreferably on one of the elliptical stress locii bands. Intermediatesection 22 of the bracket has an insulating strip 23 wrapped therearoundand embraced by a band 24 of conductive material. Band 24 carriescontact 25 normally engaging a contact 35 on pull ribbon or strip 40.The parameters are so selected that, in the closed position of thecircuit L breaker illustrated, strip 40 is bent inward in a shallow V.This increases the pressure of contacts 25, 35 and, as explained in saidapplication Ser. No. 374,918, results in the contact pressure beingmaintained at full value, or even increased, during expansion of strip40 and right up to the instant contacts 25, 35 are snapped apart bysnapping of vane 10 to its restored position. A conductive strip 26extends from band 24.

Insulated high resistance wire 30 has one end welded or soldered to vane10 at point 33 and its other end welded or soldered to band 24 at point34. Wire 30 is thus in shunt with contacts 25, 35. A grounded battery56, or other source of potential is schematically illustrated asconnected to the end 21 of bracket 20. and a grounded load 55 isschematically illustrated as connected to strip 26. This schematicillustration represents any typical load circuit incorporating thecircuit breaker. For explanation purposes, load 55 may represent a shortcircuit point in the load circuit.

With switch 57 closed, current flows from battery 56 through switch 57,bracket 21, vane 10, strip 40 from both ends to contact 35, contact 25,band 24, strip 26, and load 55 to ground. Due to its high resistance andits shunting by contacts 25, 35, substantially no current flows throughwire 30. Strip 40 has a low resistance, so that the heating due tocurrent flow therethrough, under normal load conditions, is insufiicientto expand strip 46 to an extent sufiicient to allow vane 10 to snap tothe restored condition.

Assume now that a short circuit or heavy overload condition occurs inload 55 (or at any other point in the circuit). The resultant greatlyincreased current flow through strip 40 heat the latter rapidly to apoint Where it expands sufficiently to allow vane 10 to snap to therestored condition. This will snap contacts 25, open, at least fullcontact pressure being maintained until the instant of snapping.

With contacts, 25, 35 open, strip would normally contract to snap thevane back to contact closing condition. However, opening of contacts 25,35 removes the shunt from wire 30, and the latter rapidly heats due tocarrying the overload. The current flow, however, is very substantiallyreduced due to the choking effect of high resistance wire 30. Wire 30thus heats strip 40 sufiiciently to maintain the strip expanded andpreventing re-closing of the circuit breaker contacts.

When the short circuit is cleared, the reduced current flow in wire 30allows strip 40 to cool and contract to snap vane 10 back to the contactclosing position, shunting wire 30. Thus, the circuit breakerautomatically re-sets, when the line fault is cleared, without manualattention.

While a specific embodiment of the invention has been shown anddescribed to illustrate the application of the tion may be embodiedotherwise without departing from such principles.

What is claimed:

1. A snap action circuit breaker comprising, in combination, asubstantially flat vane of resilient material having a substantiallylinear preset deformation extending thereacross, said deformation beinginterrupted intermediate its ends at points substantially equidistantfrom the vane center to leave the central area of the vane free ofpreset deformation; means secured to and mounting said vane at a pointspaced laterally from said deformation whereby, under opposed bendingstresses periodically applied to and released from points adjacent theouter ends of said deformation, in directions parallel to saiddeformation, to effect snapping of the vane between abending-stress-deformed position, in which the vane is bent about a linebisecting the line of deformation at an angle of substantially and arestored initial preset position, the free portion of the vane willpivot about such mounting point; a heat expansible element having itsopposite ends secured to said vane at points adjacent the outer ends ofsaid deformation and, in its cool and contracted condition, holding saidvane in such stress-dcforrned condition; a pair of normally closedcircuit controlling contacts, one carried by the free portion of thevane and the other fixed relative to the vane mounting point; heatingmeans for said element including a circuit controlled by said contacts,said heating means, during normal current flow through the circuitcontrolled by said contacts, heating said element insuificiently toappreciably expand the same and, during abnormally high current flowthrough the circuit controlled by said contacts as a result of a circuitfault, heating said element an amount suflicient to expand the same toan extent releasing the vane to snap to such initial pre-set position toopen said contacts; and means operable, responsive to opening of saidcontacts, to maintain the high heating of said element duringcontinuance of the circuit fault.

2. A snap action circuit breaker comprising, in combination, asubstantially flat vane of resilient material having a substantiallylinear preset deformation extending thereacross, said deformation beinginterrupted intermediate its ends at points substantially equidistantfrom the vane center to leave the central area of the vane free ofpreset deformation; means secured to and mounting said vane at a pointspaced laterally from said deformation whereby, under opposed bendingstresses periodically applied to and released from points adjacent theouter ends of said deformation, in directions parallel to saiddeformation, to effect snapping of the vane between abending-stress-deformed position, in which the vane is bent about a linebisecting the line of deformation at an angle of substantially 90, and arestored initial preset position, the free portion of the vane willpivot about such mounting point; a heat expansible element having itsopposite ends secured to said vane at points adjacent the outer ends ofsaid deformation and, in its cool and contracted condition, holding saidvane in such stress-deformed condition; a pair of normally closedcircuit controlling contacts, one carried by the free portion of thevane and the other fixed relative to the vane mounting point; heatingmeans for said element including a circuit controlled by said contacts,said heating means, during normal current flow through the circuitcontrolled by said contacts, heating said element insufficiently toappreciably expand the same and, during abnormally high current flowthrough the circuit controlled by said contacts as a result of a circuitfault, heating said element an amount sufficient to expand the same toan extent releasing the vane to snap to such initial pre-set position toopen said contacts; a high resistance conductor connected acrosssaidcontacts, and normally shunted thereby, said conductor being in heattransfer relation with said element and operable, responsive to openingof said contacts and resultinvention principles, it will be understoodthat the inven- 7'; ant abnormally high current flow through saidconductor,

to maintain the high heating of said element during continuance of thecircuit fault.

3. A snap action circuit breaker, comprising, in combination, asubstantially fiat vane of resilient material having a substantiallylinear preset deformation extending thereacross, said deformation beinginterrupted intermediate its ends at points substantially equidistantfrom the vane center to leave the central area of the vane free ofpreset deformation; means secured to and mounting said vane at a pointspaced laterally from said deformation whereby, under opposed bendingstresses periodically applied to and released from points adjacent theouter ends of said deformation, in directions parallel to saiddeformation, to effect snapping of the vane between abendingstress-deformed position, in which the vane is bent about a linebisecting the line of deformation at an angle of substantially 90, and arestored initial preset position, the free portion of the vane willpivot about such mounting point; a heat expansible electricallyconductive having its opposite ends secured to said vane at pointsadjacent the outer ends of said deformation and, in its cool andcontracted condition, holding said vane in such stress-deformedcondition; a pair of normally closed con tacts controlling a circuitincluding said element, one carried by the free portion of the vane andthe other fixed relative to the vane mounting point; said element,during normal current flow through the circuit including said contactsand said element, being heated insufficiently to appreciably expand thesame and, during abnormally high current flow through the circuitincluding said contacts and said element as a result of a circuit fault,being heated an amount sufficient to expand the same to an extentreleasing the vane to snap to such initial pre-set position to open saidcontacts; and means operable, respon sive to opening of said contacts,to maintain the high heating of said element during continuance of thecircuit fault.

4. A snap action circuit breaker, comprising, in combination, asubstantially fiat vane of resilient material having a substantiallylinear preset deformation extending thereacross, said deformation beinginterrupted intermediate its ends at points substantially equidistantfrom the vane center to leave the central area of the vane free ofpreset deformation; means secured to and mounting said vane at a pointspaced laterally from said deformation whereby, under opposed bendingstresses periodically applied to and released from points adjacent theouter ends of said'deformation, in directions parallel to saiddeformation, to effect snapping of the vane between abendingstress-deformed position, in which the vane is bent about a linebisecting the line of deformation at an angle of substantially 90, and arestored initial preset position, the free portion of the vane willpivot about such mounting point; a heat expansible electricallyconductive element having its opposite ends secured to said vane atpoints adjacent the outer ends of said deformation and, in its cool andcontracted condition, holding said vane in such stress-deformedcondition; a pair of normally closed contacts controlling a circuitincluding said element, one carried by the free portion of the vane andthe other fixed relative to the vane mounting point; said element,during normal current flow through the circuit including said contactsand said element, being heated insufficiently to appreciably expand thesame and, during abnormally high current fioW through the circuitincluding said contacts and said element as a result of a circuit fault,being an amount sufiicient to expand the same to an extent releasing thevane to snap to such initial pre-set position to open said contacts; anda high resistance conductor connected across said contacts, and normallyshunted thereby, said conductor being in heat transfer relation withsaid element and operable, responsive to opening of said contacts andresultant abnormally high current flow through said conductor, tomaintain the high heating of said element during continuance of thecircuit fault.

5. A snap action circuit breaker comprising, in combination, asubstantially flat vane of resilient material having a substantiallylinear preset deformation extending thereacross, said deformation beinginterrupted intermediate its ends at points substantially equidistantfrom the vane center to leave the central area of the vane free ofpreset deformation; a member secured to and mounting said vane at apoint spaced laterally from said deformawhereby, under opposed bendingstresses periodically applied to and released from points adjacent theouter ends of said deformation, in directions parallel to saiddeformation, to effect snapping of the vane between a b.nding-stress-deformed position, in which the vane is bent about a linebisecting the line of deformation at an angle of substantially 90, and arestored initial preset position, the free portion of the vane Willpivot about such mounting point; a heat expansible electricallyconducti- /e element having its opposite ends secured to said vane atpoints adjacent the outer ends of said deformation and, in its cool andcontracted condition, holding said vane in such stress-deformedcondition; said element, in the stress deformed condition of the vane,having at least its intermediate portion spaced from the surface of saidvane and, in the restored position of the vane, lying along the surfaceof the latter; a pair of normally closed contacts controlling a circuitincluding said element, one carried by said element and the othermounted on said member; said element, during normal current flow throughthe circuit including said contacts and said element, being heatedinsutiiciently to appreciably expand the same and during abnormally highcurrent flow through the circuit including said contacts and saidelement, as a result of a circuit fault, being heated an amountsufiicient to expandthe same to an extent releasing the vane to snap tosuch initial preset position to open said contacts; and means operable,responsive to opening of said contacts, to maintain the high heating ofsaid element during continuance of the circuit fault.

6. A snap action circuit breaker, comprising, in combination, asubstantially fiat vane of resilient material having a substantiallylinear preset deformation extending thereacross, said deformation beinginterrupted intermediate its ends at points substantially equidistantfrom the vane center to leave the central area of the vane free ofpreset deformation; a member secured to and mounting said vane at apoint spaced laterally from said deformation whereby, under opposedbending stresses periodically applied to and released from pointsadjacent the outer ends of said deformation, in directions parallel tosaid deformation, to effect snapping of the vane between abending-stress-deformed position, in which the vane is bent about a linebisecting the line of deformation at an angle of substantially 90, and arestored initial preset position, the free portion of the vane Willpivot about such mounting point; a heat expansibie electricallyconductive element having its opposite ends secured to said vane atpoints adjacent the outer ends of said deformation and, in its cool andcontracted condition, holding said vane in such stress-deformedcondition; said element in the stress-deformed condition of the vane,having at least its intermediate portion spaced from the surface of saidvane and, in the restored position of the vane, lying along the surfaceof the latter; a pair of normally closed contacts controlling a circuitincluding said element, one carried by said element and the othermounted on said member; said element, during normal current flow throughthe circuit including said contacts and said element, being heatedinsufliciently to appreciably expand the same and during abnormally highcurrent flow through the circuit including said contacts and saidelement, as a result of a circuit fault, being heated an amountsuificient to expand the same to an extent releasing the vane to snap tosuch initial pre-set position to open said contacts; and a highresistance conductor connected across said contacts, and normallyshunted thereby, said conductor being in heat transfer relation withsaid element and operable, responsive to opening of said contacts andresultant abnormally high current flow through said conductor, tomaintain the high heating of said element during continuance of thecircuit fault.

7. A snap action circuit breaker, comprising, in combination, asubstantially fiat vane of electrically conductive spring metal having asubstantially linear preset deformation extending thereacross, saiddeformation being interrupted intermediate its ends at pointssubstantially equidistant from the vane center to leave the central areaof the vane free of preset deformation; an electrically conductivemember secured to and mounting said vane at a point spaced laterallyfrom said deformation whereby, under opposed bending stressesperiodically applied to and released from points adjacent the outer endsof said deformation, in directions parallel to said deformation, toeffect snapping of the vane between a bending-stressdeformed position,in which the vane is bent about a line bisecting the line of deformationat an angle of substantially 90, and a restored initial preset position,the free portion of the vane will pivot about such mounting point; aheat expansible electrically conductive element having its opposite endssecured to said vane at points adjacent the outer ends of saiddeformation and, in its cool and contracted condition, holding said vanein such stress-deformed condition; said element, in the stressdeformedcondition of the vane, having at least its intermediate portion spacedfrom the surface of said vane and, in the restored position of the vane,lying along the surface of the latter; a pair of normally closedcontacts controlling a circuit including said element, said member, andsaid vane, one carried by said element and the other mounted on saidmember in insulated relation thereto; said element, during normalcurrent flow through the circuit including said contacts, said element,said member, and said vane, being heated insufficiently to appreciablyexpand the same and during abnormally high current flow through thecircuit including said contacts, said element, said member, and saidvane as a result of a circuit fault, being heated an amount suiiicientto expand the same to an extent releasing the vane to snap to suchinitial pre-set position to open said contacts; and means operable,responsive to opening of said contacts, to maintain the high heating ofsaid element during continuance of the circuit fault.

8. A snap action circuit breaker comprising, in com bination, asubstantially flat vane of electrically conductive spring metal having asubstantially linear preset deformation extending thereacross, saiddeformation being interrupted intermediate ends at points substantiallyequidistant from the vane center to leave the central area of the vanefree of preset deformation; an electrically conductive member secured toand mounting said vane at a point spaced laterally from said deformationwhereby, under opposed bending stresses periodically applied to andreleased from points adjacent the outer ends of said deformation, indirections parallel to said deformation, to effect snapping of the vanebetween a bending-stressdeforrned position, in which the vane is bentabout a line bisecting the line of deformation at an angle ofsubstantially 90, and a restored initial preset position, the freeportion of the vane will pivot about such mounting point; a heatexpansible electrically conductive element having its opposite endssecured to said vane at points adjacent the outer ends of saiddeformation and, in its cool and contracted condition, holding said vanein such stress-deformed condition; said element, in the stressdeformedcondition of the vane, having at least its intermediate portion spacedfrom the surface of said vane and, in the restored position of the vane,lying along the surface of the latter; a pair of normally closedcontacts controlling a circuit including said element, said iember, andsaid vane, one carried by said element and the other mounted on saidmember in insulated relation thereto; said element, during normalcurrent flow through the circuit including said contacts, said element,said member, and said vane, being heated insufficiently to appreciablyexpand the same and during abnormally high current flow through thecircuit including said contacts, said element, said member, and saidvane as a result of a circuit fault, being heated an amount sufficent toexpand the same to an extent releasing the vane to snap to such initialpre-set position to open said contacts; and a high resistance conductorconnected across said contacts, and normally shunted thereby, saidconductor being in heat transfer relation with said element andoperable, responsive to opening of said contacts and resultantabnormally high current flow through said conductor, to maintain thehigh heating of said element during continuance of the circuit fault.

9. A snap action circuit breaker comprising, in combination, asubstantially flat and rectangular vane of electrically conductivespring metal having a substantially linear preset deformation extendingthereacross along a diagonal; said deformation being interruptedintermediate its ends at points substantially equidistant from the vanecenter to leave the central area of the vane free of preset deformation;an electrically conductive member secured to and mounting said vane at apoint spaced laterally from said deformation whereby, under opposedbending stresses periodically applied to and released from pointsadjacent the outer ends of said deformation, in directions parallel tosaid deformation, to effect snapping of the vane between abending-stresscieformed position, in which the vane is bent about a linebisecting the line of deformation at an angle of substantially and arestored intial preset position, the free portion of the vane Will pivotabout such mounting point; a heat expansible electrically conductiveelement having its opposite ends secured to said vane at points adjacentthe outer ends of said deformation and, in its cool and contractedcondition, holding said vane in such stress-deformed condition; saidelement, in the stress deformed condition of the vane, having at leastits intermediate portion spaced from the surface of said vane and, inthe restored position of the vane, lying along the surface of thelatter; a pair of normally closed contacts controlling a circuitincluding said element, said member, and said vane, one carried by saidelement and the other mounted on said member in insulated relationthereto; said element, during normal current flow through the circuitincluding said contacts, said element, said member, and said vane, beingheated insufficiently to appreciably expand the same and duringabnormally high current flow through the circuit including saidcontacts, said element, said member, and said vane as a result of acircuit fault, being heated an amount suflicient to expand the same toan extent releasing the vane to snap to such initial pre-set postion toopen said contacts; and means operable, responsive to opening of saidcontacts, to maintain the high heating of said element duringcontinuance of the circuit fault.

10. A snap action circuit breaker comprising, in combination, asubstantially flat and rectangular vane of electrically conductivespring metal having a substantially linear preset deformation extendingthereacross along a diagonal, said deformation being interruptedintermediate its ends at points substantially equidistant from the vanecenter to leave the central area of the vane free of preset deformation;an electrically conductive member secured to and mounting said vane at apoint spaced laterally from said deformation whereby, under opposedbending stresses periodically applied to and released from pointsadjacent the outer ends of said deformation, in directions parallel tosaid deformation, to effect snapping of the vane between abending-stress-deformed position, in which the vane is bent about a linebisecting the line ll of deformation at an angle of substantially 90,and a restored initial preset position, the f ee portion of the vanewill pivot about such mounting point; a heat expansible electricallyconductive element having its opposite ends secured to said vane atpoints adjacent tne outer ends of said deformation and, in its cool andcontracted condition, holding said vane in such stress-deformedcondition; said element, in the stress-deformed condition of the vane,having at least its intermediate portion spaced from the surface of saidvane and, in the restored position of the vane, lying along the surfaceof the latter; a pair of normally closed contacts controlling a circuitincluding said element, said member, and said vane, one carried by saidelement and the other mounted on said member in insulated relationthereto: said element, during normal current flow through the circuitincluding said contacts, said element, said member, and said i beingheated insufiiciently to appreciably expand the and during abnormallyhigh current flow through the circuit including said contacts, saidelement, said member, and said vane as a result of a circuit fault,being heated an amount sufficient to expand the same to an extentreleasing the vane to snap to such iniiial pre-set position to open saidcontacts; and a high r sistance conductor connected across saidcontacts, and normally shunted thereby, said conductor being in heattransfer relation with said element and operable, responsive to openingof said contacts and resultant abnormally high current flow through saidconductor, to maintain the high heating of said element duringcontinuance of the circuit fault.

11. A snap action circuit breaker comprising, in combination, asubstantially flat and rectangular vane of electrically conductivespring metal having a substantially linear preset deformation extendingthereacross along a diagonal, said deformation being interruptedintermediate its ends at points substantially equidistant from the vanecenter to leave the central area of the vane free of preset deformationand with curvilinear stress concentration locii concentric with the vanecenter; an electrically conductive member secured to and mounting saidvane at a point on one of said locii spaced laterally from saiddeformation whereby, under opposed bending stresses periodically appliedto and released from points adjacent the outer ends of said deformation,in directions parallel to said deformation, to effect snapping of thevane between a bendiug-stress-deformed position, in which the vane isbent about a line bisecting the line of deformation at an angle ofsubstantially 90, and a restored initial preset position, the treeportion of the vane will pivot about such mounting points; a heatexpansible electrically conductive element having its opposite endssecured to said vane at points adjacent the outer ends of saiddeformation and, in its cool and contracted condition, holding said vanein such stress-deformed condition; said element, in the stress-deformedcondition of the vane, having at least its intermediate portion spacedfrom the surface of said vane and, in the restored position of the vane,lying along the surface of the latter; a pair of normally closedcontacts controlling a circuit including said element, said member, andsaid vane, one carried by said element and the other mounted on saidmember in insulated relation thereto; said element, during normalcurrent flow through the circuit including said contacts, said element,said member, and said vane, being heated insufficiently to appreciablyexpand the same and during abnormally high current flow through thecircuit including said contacts, said element, said member, and saidvane as a result of a circuit fault, being heated an amount sufiicientto expand the same to an extent releasing the vane to snap to suchinitial pre-set position to open said contacts; and means operable,responsive to opening of said contacts, to maintain the iigh heating ofsaid element during continuance of the circuit fault.

12. A snap action circuit breaker comprising, in cornall) bination, asubstantially flat and rectangular vane of electrically conductivespring metal having a substantially linear preset deformation extendingthereacross along a diagonal, said deformation being interruptedintermediate its ends at points substantially equidistant from the vanecenter to leave the central area of the vane free of preset deformationand with curvilinear stress concentration locii concentric with the vanecenter; an electrically conductive member secured to and mounting saidvane at a point on one of said locii spaced laterally from saiddeformation whereby, under opposed bending stresses periodically appliedto and released from points adjacent the outer ends of said deformation,in directions parallel to said deformation, to effect snapping of thevane between a bendingstress-deformed position, in which the vane isbent about a line bisecting the line of deformation at an angle ofsubstantially 90, and a restored initial preset position, the freeportion of the vane will pivot about such mounting point; a heatexpansible electrically conductive element having its opposite endssecured to said vane at points adjacent the outer ends of saiddeformation and, in its cool and contracted condition, holding said vanein stress-deformed condition; said element, in the stress-deformedcondition of the vane, having at least its intermediate portion spacedfrom the surface of said vane and, in the restored position of the vane,lying along the surface of the latter; a pair of normally closedcontacts controlling a circuit including said element, said member, andsaid vane, one carried by said element and the other mounted on saidmember in insulated relation thereto; the intermediate portion of saidelement, in the closed position of said contacts, being bent by thelatter toward the vane surface to maintain full contact pressure untilsnapping of the vane to the restored position; said element, duringnormal current flow through the circuit including said contacts, saidelement, said member, and said vane, being heated insufliciently toappreciably expand the same and during abnormally high current flowthrough the circuit including said contacts, said element, said member,and said vane as a result of a circuit fault, being heated an amountsufficient to expand the same to an extent releasing the vane to snap tosuch initial pre-set position to open said contacts; and a highresistance conductor connected across said contacts, and normallyshunted thereby, said conductor being in heat transfer relation withsaid element and operable, responsive to opening of said contacts andresultant abnormally high current flow through said conductor, tomaintain the high heating of said element during continuance of thecircuit fault.

13. A snap action circuit breaker comprising, in combination, asubstantially flat and rectangular vane of electrically conductivespring metal having a substantially linear preset deformation extendingthereacross along a diagonal, said deformation being interruptedintermediate its ends at points substantially equidistant from the vanecenter to leave the central area of the vane free of present deformationand with curvilinear stress concentration locii concentric with the vanecenter; an electrically conductive member secured to and mounting saidvane at a point on one of said locii spaced laterally from saiddeformation whereby, under opposed bending stresses periodically appliedto and released from points adjacent the outer ends of said deformation,in directions parallel to said deformation, to effect snapping of thevane between a bending-stress-deformed position, in which the vane isbent about a line bisecting the line of deformation at an angle ofsubstantially 90, and a restored initial preset position, the freeportion of the vane will pivot about such mounting point; a heatexpansible electrically conductive element having its opposite endssecured to said vane at points adjacent the outer ends of saiddeformation and, in its cool and contracted condition, holding said vanein such stress-deformed condition; said element, in the stress-deformedcondition of the vane,

13 having at least its intermediate portion spaced from the surface ofsaid vane and, in the restored position of the vane, lying along thesurface of the latter; a pair of normally closed contacts controlling acircuit including said element, said member, and said vane, one carriedby said element and the other mounted on said member in insulatedrelation thereto; the intermediate portion of said element, in theclosed position of said contacts, being bent by the latter toward thevane surface to maintain full contact pressure until snapping of thevane to the restored position; said element, during normal current flowthrough the circuit including said contacts, said element, said member,and said vane, being heated insufiiciently to appreciably expand thesame and during abnormally high current flow through the circuitincluding said contacts, said element, said member, and said vane as aresult of a circuit fault, being heated an amount sufficient to expandthe same to an extent releasing the vane to snap to such initial pre-setposition to open said con tacts; and a high resistance conductorconnected across said contacts, and normally shunted thereby, saidconductor being in heat transfer relation with said element andoperable, responsive to opening of said contacts and resultantabnormally high current flow through said conductor, to maintain thehigh heating of said element during continuance of the circuit fault;said conductor, upon clearing of such fault with resultant reducedcurrent flow through said conductor, cooling to an extent sufficient forcontraction of said element to snap the vane to the stress-deformedposition to re-close said contacts.

References Cited in the file of this patent UNITED STATES PATENTS2,249,837 Lee July 22, 1941 2,286,053 Bletz June 9, 1942 2,616,996Beeman Nov. 4, 1952

